Although current research indicates that there are no biological risks associated with exposure to electromagnetic fields, the strategy of prudent avoidance is practical in terms of sitting exposure limits for the general public and even for workers in the electrical power sector. On this basis, exposure limits have been set for alternating power frequency magnetic fields. Air core reactors, like other power equipment (including transmission lines, etc.) are subject to these criteria.
Current practice to achieve compliance is based on the practice of increasing distance from the source. Essentially, exposure is limited by the use of barriers, actual or imposed, thereby controlling the area surrounding an energized dry type air core reactor. Actual barriers include security-fenced areas, whereas imposed barriers include the use of elevated support structures, which increase the distance between an energized dry type air core reactor and an individual at ground level. These approaches produce the desired result of limiting the strength of magnetic field to which an individual is exposed, at least in part. However, the drawback is an increase in real estate required for an installation. This has both economic consequences and land availability issues. In many urban settings electrical substation real estate is limited and increased “magnetic clearance” is therefore not a viable option. Therefore, another methodology for reducing the magnetic field strength in areas accessible by the general public and electrical power workers is required.